/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:		arm_cos_f32.c
*
* Description:	Fast cosine calculation for floating-point values.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated.
* -------------------------------------------------------------------- */

#include "arm_math.h"
/**
 * @ingroup groupFastMath
 */

/**
 * @defgroup cos Cosine
 *
 * Computes the trigonometric cosine function using a combination of table lookup
 * and cubic interpolation.  There are separate functions for
 * Q15, Q31, and floating-point data types.
 * The input to the floating-point version is in radians while the
 * fixed-point Q15 and Q31 have a scaled input with the range
 * [0 +0.9999] mapping to [0 2*pi), Where range excludes 2*pi.
 *
 * The implementation is based on table lookup using 256 values together with cubic interpolation.
 * The steps used are:
 *  -# Calculation of the nearest integer table index
 *  -# Fetch the four table values a, b, c, and d
 *  -# Compute the fractional portion (fract) of the table index.
 *  -# Calculation of wa, wb, wc, wd
 *  -# The final result equals <code>a*wa + b*wb + c*wc + d*wd</code>
 *
 * where
 * <pre>
 *    a=Table[index-1];
 *    b=Table[index+0];
 *    c=Table[index+1];
 *    d=Table[index+2];
 * </pre>
 * and
 * <pre>
 *    wa=-(1/6)*fract.^3 + (1/2)*fract.^2 - (1/3)*fract;
 *    wb=(1/2)*fract.^3 - fract.^2 - (1/2)*fract + 1;
 *    wc=-(1/2)*fract.^3+(1/2)*fract.^2+fract;
 *    wd=(1/6)*fract.^3 - (1/6)*fract;
 * </pre>
 */

/**
* @addtogroup cos
* @{
*/


/**
* \par
* <b>Example code for Generation of Cos Table:</b>
* tableSize = 256;
* <pre>for(n = -1; n < (tableSize + 2); n++)
* {
*	cosTable[n+1]= cos(2*pi*n/tableSize);
* } </pre>
* where pi value is  3.14159265358979
*/

static const float32_t cosTable[260] = {
	0.999698817729949950f, 1.000000000000000000f, 0.999698817729949950f,
	0.998795449733734130f, 0.997290432453155520f, 0.995184719562530520f,
	0.992479562759399410f, 0.989176511764526370f,
	0.985277652740478520f, 0.980785250663757320f, 0.975702106952667240f,
	0.970031261444091800f, 0.963776051998138430f, 0.956940352916717530f,
	0.949528157711029050f, 0.941544055938720700f,
	0.932992815971374510f, 0.923879504203796390f, 0.914209783077239990f,
	0.903989315032958980f, 0.893224298954010010f, 0.881921291351318360f,
	0.870086967945098880f, 0.857728600502014160f,
	0.844853579998016360f, 0.831469595432281490f, 0.817584812641143800f,
	0.803207516670227050f, 0.788346409797668460f, 0.773010432720184330f,
	0.757208824157714840f, 0.740951120853424070f,
	0.724247097969055180f, 0.707106769084930420f, 0.689540565013885500f,
	0.671558976173400880f, 0.653172850608825680f, 0.634393274784088130f,
	0.615231573581695560f, 0.595699310302734380f,
	0.575808167457580570f, 0.555570244789123540f, 0.534997642040252690f,
	0.514102756977081300f, 0.492898195981979370f, 0.471396744251251220f,
	0.449611335992813110f, 0.427555084228515630f,
	0.405241310596466060f, 0.382683426141738890f, 0.359895050525665280f,
	0.336889863014221190f, 0.313681751489639280f, 0.290284663438797000f,
	0.266712754964828490f, 0.242980182170867920f,
	0.219101235270500180f, 0.195090323686599730f, 0.170961886644363400f,
	0.146730467677116390f, 0.122410677373409270f, 0.098017141222953796f,
	0.073564566671848297f, 0.049067676067352295f,
	0.024541229009628296f, 0.000000000000000061f, -0.024541229009628296f,
	-0.049067676067352295f, -0.073564566671848297f, -0.098017141222953796f,
	-0.122410677373409270f, -0.146730467677116390f,
	-0.170961886644363400f, -0.195090323686599730f, -0.219101235270500180f,
	-0.242980182170867920f, -0.266712754964828490f, -0.290284663438797000f,
	-0.313681751489639280f, -0.336889863014221190f,
	-0.359895050525665280f, -0.382683426141738890f, -0.405241310596466060f,
	-0.427555084228515630f, -0.449611335992813110f, -0.471396744251251220f,
	-0.492898195981979370f, -0.514102756977081300f,
	-0.534997642040252690f, -0.555570244789123540f, -0.575808167457580570f,
	-0.595699310302734380f, -0.615231573581695560f, -0.634393274784088130f,
	-0.653172850608825680f, -0.671558976173400880f,
	-0.689540565013885500f, -0.707106769084930420f, -0.724247097969055180f,
	-0.740951120853424070f, -0.757208824157714840f, -0.773010432720184330f,
	-0.788346409797668460f, -0.803207516670227050f,
	-0.817584812641143800f, -0.831469595432281490f, -0.844853579998016360f,
	-0.857728600502014160f, -0.870086967945098880f, -0.881921291351318360f,
	-0.893224298954010010f, -0.903989315032958980f,
	-0.914209783077239990f, -0.923879504203796390f, -0.932992815971374510f,
	-0.941544055938720700f, -0.949528157711029050f, -0.956940352916717530f,
	-0.963776051998138430f, -0.970031261444091800f,
	-0.975702106952667240f, -0.980785250663757320f, -0.985277652740478520f,
	-0.989176511764526370f, -0.992479562759399410f, -0.995184719562530520f,
	-0.997290432453155520f, -0.998795449733734130f,
	-0.999698817729949950f, -1.000000000000000000f, -0.999698817729949950f,
	-0.998795449733734130f, -0.997290432453155520f, -0.995184719562530520f,
	-0.992479562759399410f, -0.989176511764526370f,
	-0.985277652740478520f, -0.980785250663757320f, -0.975702106952667240f,
	-0.970031261444091800f, -0.963776051998138430f, -0.956940352916717530f,
	-0.949528157711029050f, -0.941544055938720700f,
	-0.932992815971374510f, -0.923879504203796390f, -0.914209783077239990f,
	-0.903989315032958980f, -0.893224298954010010f, -0.881921291351318360f,
	-0.870086967945098880f, -0.857728600502014160f,
	-0.844853579998016360f, -0.831469595432281490f, -0.817584812641143800f,
	-0.803207516670227050f, -0.788346409797668460f, -0.773010432720184330f,
	-0.757208824157714840f, -0.740951120853424070f,
	-0.724247097969055180f, -0.707106769084930420f, -0.689540565013885500f,
	-0.671558976173400880f, -0.653172850608825680f, -0.634393274784088130f,
	-0.615231573581695560f, -0.595699310302734380f,
	-0.575808167457580570f, -0.555570244789123540f, -0.534997642040252690f,
	-0.514102756977081300f, -0.492898195981979370f, -0.471396744251251220f,
	-0.449611335992813110f, -0.427555084228515630f,
	-0.405241310596466060f, -0.382683426141738890f, -0.359895050525665280f,
	-0.336889863014221190f, -0.313681751489639280f, -0.290284663438797000f,
	-0.266712754964828490f, -0.242980182170867920f,
	-0.219101235270500180f, -0.195090323686599730f, -0.170961886644363400f,
	-0.146730467677116390f, -0.122410677373409270f, -0.098017141222953796f,
	-0.073564566671848297f, -0.049067676067352295f,
	-0.024541229009628296f, -0.000000000000000184f, 0.024541229009628296f,
	0.049067676067352295f, 0.073564566671848297f, 0.098017141222953796f,
	0.122410677373409270f, 0.146730467677116390f,
	0.170961886644363400f, 0.195090323686599730f, 0.219101235270500180f,
	0.242980182170867920f, 0.266712754964828490f, 0.290284663438797000f,
	0.313681751489639280f, 0.336889863014221190f,
	0.359895050525665280f, 0.382683426141738890f, 0.405241310596466060f,
	0.427555084228515630f, 0.449611335992813110f, 0.471396744251251220f,
	0.492898195981979370f, 0.514102756977081300f,
	0.534997642040252690f, 0.555570244789123540f, 0.575808167457580570f,
	0.595699310302734380f, 0.615231573581695560f, 0.634393274784088130f,
	0.653172850608825680f, 0.671558976173400880f,
	0.689540565013885500f, 0.707106769084930420f, 0.724247097969055180f,
	0.740951120853424070f, 0.757208824157714840f, 0.773010432720184330f,
	0.788346409797668460f, 0.803207516670227050f,
	0.817584812641143800f, 0.831469595432281490f, 0.844853579998016360f,
	0.857728600502014160f, 0.870086967945098880f, 0.881921291351318360f,
	0.893224298954010010f, 0.903989315032958980f,
	0.914209783077239990f, 0.923879504203796390f, 0.932992815971374510f,
	0.941544055938720700f, 0.949528157711029050f, 0.956940352916717530f,
	0.963776051998138430f, 0.970031261444091800f,
	0.975702106952667240f, 0.980785250663757320f, 0.985277652740478520f,
	0.989176511764526370f, 0.992479562759399410f, 0.995184719562530520f,
	0.997290432453155520f, 0.998795449733734130f,
	0.999698817729949950f, 1.000000000000000000f, 0.999698817729949950f,
	0.998795449733734130f
};

/**
 * @brief  Fast approximation to the trigonometric cosine function for floating-point data.
 * @param[in] x input value in radians.
 * @return cos(x).
 */


float32_t arm_cos_f32(
    float32_t x)
{
	float32_t cosVal, fract, in;
	int32_t index;
	uint32_t tableSize = (uint32_t) TABLE_SIZE;
	float32_t wa, wb, wc, wd;
	float32_t a, b, c, d;
	float32_t* tablePtr;
	int32_t n;
	float32_t fractsq, fractby2, fractby6, fractby3, fractsqby2;
	float32_t oneminusfractby2;
	float32_t frby2xfrsq, frby6xfrsq;

	/* input x is in radians */
	/* Scale the input to [0 1] range from [0 2*PI] , divide input by 2*pi */
	in = x * 0.159154943092f;

	/* Calculation of floor value of input */
	n = (int32_t) in;

	/* Make negative values towards -infinity */
	if(x < 0.0f) {
		n = n - 1;
	}

	/* Map input value to [0 1] */
	in = in - (float32_t) n;

	/* Calculation of index of the table */
	index = (uint32_t)(tableSize * in);

	/* fractional value calculation */
	fract = ((float32_t) tableSize * in) - (float32_t) index;

	/* Checking min and max index of table */
	if(index < 0) {
		index = 0;
	} else if(index > 256) {
		index = 256;
	}

	/* Initialise table pointer */
	tablePtr = (float32_t*) & cosTable[index];

	/* Read four nearest values of input value from the cos table */
	a = tablePtr[0];
	b = tablePtr[1];
	c = tablePtr[2];
	d = tablePtr[3];

	/* Cubic interpolation process */
	fractsq = fract * fract;
	fractby2 = fract * 0.5f;
	fractby6 = fract * 0.166666667f;
	fractby3 = fract * 0.3333333333333f;
	fractsqby2 = fractsq * 0.5f;
	frby2xfrsq = (fractby2) * fractsq;
	frby6xfrsq = (fractby6) * fractsq;
	oneminusfractby2 = 1.0f - fractby2;
	wb = fractsqby2 - fractby3;
	wc = (fractsqby2 + fract);
	wa = wb - frby6xfrsq;
	wb = frby2xfrsq - fractsq;
	cosVal = wa * a;
	wc = wc - frby2xfrsq;
	wd = (frby6xfrsq) - fractby6;
	wb = wb + oneminusfractby2;

	/* Calculate cos value */
	cosVal = (cosVal + (b * wb)) + ((c * wc) + (d * wd));

	/* Return the output value */
	return (cosVal);

}

/**
 * @} end of cos group
 */
